1. Field of the Invention
This invention is directed toward improvements in fluid-driven rotary dental tools and, more particularly, is related to a pressure-sensitive grip for a dental hand drill which allows the operator to easily, accurately and continuously control the speed of the drill.
2. Description of the Prior Art
There exists many different control mechanisms and techniques for controlling the pressure fluid to pneumatic motors of power operated tools such as those utilized to control the air in a compressed air turbine driven dental drilling machine. Some of such control mechanisms incorporate foot actuated switches or valves which control the supply of electricity or air via a control valve. Such foot pedal mechanisms have long been recognized as being less than desirable owing to various annoyances and inconveniences as pointed out in the U.S. patent to Kopp (No. 3,244,846).
As a result of the recognized deficiencies of foot switches, pedals, and the like, subsequent artisans have proposed the fitting of electric switches and control mechanisms on the hand or angle piece of the drill, as exemplified by the Kopp patent. Unfortunately, such prior art attempts have been less than entirely successful in providing an inexpensive, convenient, easily operable precision device for controlling the speed of the drill. One of the main difficulties of prior art control mechanisms as exemplified by said Kopp patent, the White patent (No. 3,256,603), and the Coss patent (No. 3,430,710) is the apparent failure to provide a means for minutely and continuously regulating the supply of air pressure, and hence the speed of the pneumatic motor or turbine of the drill, over a wide range of desired limits which is both inexpensive and noncomplex. Other prior U.S. Patents in this area of which I am aware include the Prufer Pat. No. 3,210,847, and the Martin Pat. No. 3,568,318. However, neither of the foregoing provide the concommitant requirements of reliability in operation and ease of use so necessary in tools of this nature.